Rotary percussion drill



Jan. 26, 1954 R. H. HOLSING ROTARY PERCUSSION DRILL Filed Jan. 20. 1949FIG, I.

FIG.

INVENTOR HIS ATTORNEYS.

Patented Jan. 26, 1954 UNITED STATES PATENT.

2,667,373 ROTARY PERCUSSION DRILL Robert H. Holsing; Canton, Ohio,assignor to The Timken Roller Bearing Company, Canton, Ohio,

a corporation of Ohio Application July 20,1949, Serial No. 105,772

4 Claims.

produce and involve danger of breakage of weak parts, accidentalseparation of the drill bit from the drill rod and binding of the partsto such an extent that separation is prevented.

The present invention is concerned with overcoming the above mentioneddisadvantages, and its principal object is to provide a strong automaticfriction grip between the drill bit and the drill rod to provide economyof manufacture, to eliminate separate fastening devices and to permiteasy separation of the parts, when desired, without accidentalseparation thereof. The invention consists principally in providing theseparable drill bit with a multisided drill rod receiving socket whichis twisted upon itself about its central longitudinal axis and inproviding the drill rod with a straight multisided end portion adaptedto be forced endwise into the twisted socket portion, thus straighteningthe twisted socket therein, whereby the tendency of the untwisted socketportion to return to its twisted position provides a friction gripbetween the corresponding sides of the socket and rod end which willfirmly hold the parts together against relative endwise and rotarymovement and which, at the same time, will permit easy separation of theparts. The invention also consists in making the twisted socket of thebit resilient so as to exert a constant pressure against the drill rodand thereby increase the frictional grip of the twisted socket on thedrill rod.

In the accompanying drawing, which forms part of this specification andwherein like symbols refer to like parts wherever they occur,

Fig. 1 is a side elevational view of a separable drill bit and rodassembly embodying my invention,

Fig. 2 is an end elevational View of the socket end of the separabledrill bit, showing the socket before it is twisted and heat treated,

Fig. 3 is a view similar to Fig. 2, showing the socket after it istwisted and heat treated,

Fig. 4 is a cross-sectional view on the line 4-45 in Fig. 1; and

Fig. 5 is a central vertical longitudinal view on the line 5-5 in Fig.1.

In the accompanying drawing, my invention is shown embodied in a rotarypercussion drill comprising a drill rod' A and a separable drill bit Btherefor having any desired number and arrangement of cutting anddrilling edges 1 at the working end thereof and a central rear wardly'opening socket 2' adapted to receive the end of said drill rod.

In accordance with the present invention, the socket 2 of the bit B isformed with a flat bottom and a multiplicity of flat side walls, saidsocket preferably being square in cross-section; The socket engaging endof the drill rod A is also of square section and is equal to or slightlyless than the square socket 2in the bit B. As shown in Fig. 3, thesquare socket 2 of the separable bit B is twisted upon itself by turningthe outer end portion of said socket relative to the inner end portionthereof about the central longitudinal axis thereof, after which thesocket is heat treated to increase the resiliency thereof. The drill rodA and separable drill bit B are then assembled by forcing the square endof the drill rod endwise in the square twisted socket 2 of the bitpreferably the full depth of said socket, thereby completely orpartially straightening or untwisting the twisted socket, depending onthe snugness of the fit of the rod in the socket.

With the parts thus assembled-the tendency of the untwisted multisidedsocket 2 of the bit B to return to its twisted condition creates astrong friction grip between the sides of the socket and thecorresponding sides of the multisided portion of the drill rod Atherein, thus firmly securing the bit to the drill rod. The socket 2 ofthe bit is twisted in the direction of the drilling rotation so that therotative force while drilling is applied at the lower portion of thesocketand-'not-against the spring tension of the upper portions of thesides thereof.

The hereinbefore described construction has several importantadvantages. It is simple and easy to manufacture and provides a strongautomatic friction grip between the drill bit and rod merely by forcingthe square end of the drill rod into the twisted square socket providedtherefor in the bit. The friction grip between the drill rod and socketprevents accidental separation of the parts and also permits easyseparation of the parts, when desired, merely by driving the bit off ofthe engaging end ofthe drill rod. Special fastening devices andthreading of the parts are dispensed with. The drill rods may varyappreciably in size and still provide a firm friction grip between thedrill rod and the socket provided therefor in the bit. The smaller sizedrill rods counteract only part of the twist in the socket of the drillbit, but still provide a sufiicient frictional grip to preventseparation of the parts and to provide equal contact for drilling. Thesocket of the drill bit and the portion of the drill rod therein may beprovided with any'desired number of cooperating fiat faces.

What I claim is:

1. A drill comprising a drill rod and a separable drill bit therefor,said drill bit having a noncircular socket that is twisted upon itselfabout its longitudinal axis in the direction that the drill is to berotated and said drill rod having a similar untwisted non-circular endportion adapted to be forced endwise into said twisted socket, therebyuntwisting said socket and thus providing a frictional grip between thesides of said socket and rod end therein.

2. A drill comprising a drill rod and a separable drill bit therefor,said drill bit having a multisided socket that is twisted upon itselfabout its longitudinal axis and said drill rod having a similaruntwisted multisided end portion adapted to be forced endwise into saidtwisted socket, thereby untwisting said socket and thus providing africtional grip between the sides of said socket and rod end therein.

3. A drill comprising a drill rod and a separable drill bit therefor,said drill bit having a substantially rectangular socket that is twistedupon itself about its longitudinal axis and said drill rod 4 having anuntwisted substantially rectangular end portion that is forced endwiseinto said twisted socket thereby untwisting said socket and thusproviding a frictional grip between the flat sides of said socket androd end therein.

4. A drill comprising a drill rod and a drill bit one of which providesan axially open socket into which the other member is axially' inserted,the socket of said one member providing a multiplicity of side walls andthe inserted end of said other member having similar side walls, theside walls of one of said members being initially and permanentlyangularly twisted about a common longitudinal axis and the side walls ofthe other of said members being axially straight, insertion of saidother member into said open socket thereby tending to reverse theangularly twisted side walls of said one of said members for creating astrong frictional grip therebetween.

ROBERT H. HOLSING.

References Cited in the file of this patent UNITED STATES PATENTS2,354,656 Annesley Aug. 1, 1944

